Method, apparatus and system for controlling a gas-fired heater

ABSTRACT

The present invention provides a system, method and apparatus for controlling a gas-fired heater connected to a fuel source via a fuel source valve that includes one or more power sources, a temperature sensor, a pilotless igniter disposed within the gas-fired heater, a flame sensor disposed within the gas-fired heater and a controller electrically connected to the one or more power sources, the temperature sensor, the pilotless igniter, the flame sensor and the fuel source valve. The controller turns the pilotless igniter on for a first time period and opens the fuel source valve whenever the temperature sensor indicates that a temperature is less than or equal to a low temperature setting. The controller also closes the fuel source valve whenever the temperature sensor indicates that the temperature is greater than or equal to a high temperature setting or the flame sensor indicates that a flame has gone out.

TECHNICAL FIELD OF THE INVENTION

The present invention relates, in general, to the field of controlsystems, and in particular, to a method, apparatus and system forcontrolling a gas-fired heater.

BACKGROUND OF THE INVENTION

Without limiting the scope of the invention, the background of theinvention is described in connection with wellhead equipment for oil andgas wells in regions that experience extremely cold winters, such as athigh altitude, or in Alaska, Canada, Siberia, etc. When temperaturesfall below freezing, or to a temperature that would disrupt normaloperations, the wellhead equipment that is installed on a producing oilor gas well to control and regulate the flow of oil or gas can freeze-upand cease to function. These freeze-ups are quite expensive becausevaluable production is lost and skilled workers have to be dispatched tothe well site to remedy the freeze-up and restore the production of oilor gas from the well. Moreover, traveling to these well sites, which aretypically in remote, hard to reach areas, is difficult and oftenhazardous. Likewise, working in below freezing conditions is alsodifficult and hazardous.

Similarly, a heater is required on some oil and gas wells in order forthe well to produce no matter what the ambient temperature is. Forexample, oil and gas wells that contain high amounts of paraffin must beheated in order to maintain a product viscosity that allows the productto be transferred. In other words, the product has a paste-like textureor is almost solid unless it is heated. As a result, these wells must beheated year around.

Over the years, many systems have been proposed to heat the wellheadequipment when the temperature drops below a specified temperature, suchas freezing (zero degrees Celsius), or when the product must be heatedso that it can be moved. The most commonly used system is theinstallation of a gas-fired heater at the well site to heat the wellheadequipment. Other more expensive, complicated, and maintenance intensivesolutions have been proposed, such as insulated jackets (e.g., U.S. Pat.No. 5,049,724 issued to Anderson on Sep. 17, 1991), infrared heaters(e.g., U.S. Pat. No. 6,776,227 issued to Beida et al on Aug. 17, 2004),and engine coolant (e.g., U.S. Pat. No. 6,032,732 issued to Yewell onMar. 7, 2000). Often these more sophisticated heating systems are justnot feasible for the remote areas that are most likely to havefreeze-ups because they typically require the installation andmaintenance of additional equipment and the storage of refined fuels torun the heaters

Gas-fired heaters, on the other hand, are often fueled by natural gasdiverted from the well, which reduces the amount of equipment that mustbe installed and maintained. But these gas-fired heaters typically relyon pilot lights to start the heaters. These standing pilots are normallylit in late fall or early winter and are not extinguished until mid tolate spring. But these pilots often go out, especially in bad weather.When the pilot light goes out and the heater is activated, the fuel gasis vented (wasted), the wellhead freezes, production volumes aredecreased and the operator's time is consumed. Moreover, the vented fuelgas poses numerous safety and environmental problems. As a result, theseexisting gas-fired heaters can be costly due to lost fuel gas volumes,lost production volumes, lost productivity of employees, the safetyconsiderations of manually lighting heaters, and the environmentalconsiderations of vented gas.

Although pilotless heaters have been used in commercial and residentialapplications for some time, these systems will not survive or functionproperly in the harsh environmental conditions at a well site (e.g.,cold, wind, moisture, corrosive elements, unclean fuel, etc.). As aresult, there is a need for a system, method and apparatus forcontrolling a gas-fired heater that is dependable, durable, efficient,inexpensive, reliable and removes the need for unsafe pilot lightingprocedures, reduces the introduction of natural gas vented into theatmosphere caused by pilot or main boiler tube flame outs, reduces theamount of human operator attendance time, as well as emergency call outsdue to flame outs, and eliminates freeze-up due to pilot or main boilertube flame outs.

SUMMARY OF THE INVENTION

The present invention provides a system, method and apparatus forcontrolling a gas-fired heater that is dependable, durable, efficient,inexpensive, reliable and removes the need for unsafe pilot lightingprocedures, reduces the introduction of natural gas vented into theatmosphere caused by pilot or main boiler tube flame outs, reduces theamount of human operator attendance time, as well as emergency call outsdue to flame outs, and eliminates freeze-up due to pilot or main boilertube flame outs. Moreover, the present invention provides a costreduction to wellhead operations which utilize any boiler tubeapplication. Savings can conservatively approach a two year payout forsystem users. Savings are experienced because there is no longer apilot, which may be lit for six months or more of the year. There isalso savings by a decrease in lost production, which is experienced whenwellhead boiler equipment is inoperative.

The present invention increases safety because there are no open flameson location, no pilot to light, no lighting procedures, no freezing dueto a pilot going out, the solenoid valve is fail safe, the electronicsare fail safe, and the circuit board was built in protection in theevent wires are hooked up wrong. In addition, the present invention canprovide numerous features, such as a built in solar panel chargingregulator, a green light to indicate the system is working properly or aproblem exists when the green light flashes, a reset button, and optionto wire in existing telemetry to send a signal incase of a systemshutdown, and an option to wire in a tank level gauge if the water levelfalls below the fire tube. The present invention can be used in anyboiler or gas-fired heater tube application, such as wellheads, naturalgas and natural gas liquids processing plants, natural gas and naturalgas liquids purification plants, and petrochemical complexes.

More specifically, the present invention provides a system forcontrolling a gas-fired heater connected to a fuel source via a fuelsource valve that includes one or more power sources, a temperaturesensor, a pilotless igniter disposed within the gas-fired heater, aflame sensor disposed within the gas-fired heater and a controllerelectrically connected to the one or more power sources, the temperaturesensor, the pilotless igniter, the flame sensor and the fuel sourcevalve. The controller turns the pilotless igniter on for a first timeperiod and opens the fuel source valve whenever the temperature sensorindicates that a temperature is less than or equal to a low temperaturesetting. The controller also closes the fuel source valve whenever thetemperature sensor indicates that the temperature is greater than orequal to a high temperature setting or the flame sensor indicates that aflame has gone out.

The one or more power sources may include a battery, a solar panel, agenerator, an AC electrical outlet or a battery that is recharged by asolar panel. The temperature sensor can indicate that the temperature isless than or equal to the low temperature setting by sending a lowtemperature signal to the controller, and indicate that the temperatureis greater than or equal to the high temperature setting by sending ahigh temperature signal to the controller. The low temperature settingand the high temperature setting can be set at the temperature sensor orthe controller.

In addition, the present invention provides an apparatus for controllinga gas-fired heater connected to a fuel source via a fuel source valvethat includes a first connector, a second connector, a third connector,a fourth connector, a fifth connector and a processor connected to thefirst, second, third, fourth and fifth connectors. During operation, theprocessor receives power from one or more power sources via the firstconnector, turns on a pilotless igniter for a first time period via thethird connector and opens the fuel source valve via the fifth connectorwhenever a temperature sensor indicates that a temperature is less thanor equal to a low temperature setting via the second connector. Theprocessor closes the fuel source valve via the fifth connector wheneverthe temperature sensor indicates that the temperature is greater than orequal to a high temperature setting via the second connector or a flamesensor indicates that a flame has gone out via the fourth connector.

The present invention also provides a method for controlling a gas-firedheater connected to a fuel source via a fuel source valve by turning apilotless igniter on for a first time period and opening the fuel sourcevalve whenever a temperature is less than or equal to a low temperaturesetting, and closing the fuel source valve whenever the temperature isgreater than or equal to a high temperature setting or a flame sensorindicates that a flame has gone out. Note that the present invention canbe implemented using a computer program embodied on a computer readablemedium wherein the above-described steps are implemented using one ormore code segments.

Moreover, the present invention provides a control kit for a gas-firedheater connected to a fuel source via a fuel source valve that includesa battery, a temperature sensor, a pilotless igniter for installationwithin the gas-fired heater, a flame sensor for installation within thegas-fired heater and a controller. The controller has a first connector

for the battery, a second connector for the temperature sensor, a thirdconnector for the pilotless igniter, a fourth connector for the flamesensor and a fifth connector for the fuel source valve. The controlleris configured or programmed to turn the pilotless igniter on for a firsttime period and open the fuel source valve whenever the temperaturesensor indicates that a temperature is less than or equal to a lowtemperature setting. The controller is also configured or programmed toclose the fuel source valve whenever the temperature sensor indicatesthat the temperature is greater than or equal to a high temperaturesetting or the flame sensor indicates that a flame has gone out.

The present invention is described in detail below with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent invention, reference is now made to the detailed description ofthe invention along with the accompanying figures and in which:

FIG. 1 is a block diagram of a control system for a gas-fired heater inaccordance with one embodiment of the present invention;

FIG. 2 is a block diagram of a controller for a gas-fired heater inaccordance with one embodiment of the present invention;

FIGS. 3A and 3B are flow charts of a method of controlling a gas-firedheater in accordance with one embodiment of the present invention;

FIGS. 4A and 4B are flow charts of a method of controlling a gas-firedheater in accordance with another embodiment of the present invention;and

FIGS. 5A and 5B are flow charts of a method of controlling a gas-firedheater in accordance with yet another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the presentinvention are discussed in detail below with respect to a pilotlessigniter system, it should be appreciated that the present inventionprovides many applicable inventive concepts that can be embodied in awide variety of specific contexts, including but not limited to, anyboiler or gas-fired heater tube application, such as wellheads, naturalgas and natural gas liquids processing plants, natural gas and naturalgas liquids purification plants, and petrochemical complexes. As aresult, the terminology used and specific embodiments discussed hereinare merely illustrative of specific ways to make and use the inventionand do not delimit the scope of the invention.

The present invention provides a system, method and apparatus forcontrolling a gas-fired heater that is dependable, durable, efficient,inexpensive, reliable and removes the need for unsafe pilot lightingprocedures, reduces the introduction of natural gas vented into theatmosphere caused by pilot or main boiler tube flame outs, reduces theamount of human operator attendance time, as well as emergency call outsdue to flame outs, and eliminates freeze-up due to pilot or main boilertube flame outs. Moreover, the present invention provides a costreduction to wellhead operations which utilize any boiler tubeapplication. Savings can conservatively approach a two year payout forsystem users. Savings are experienced because there is no longer apilot, which may be lit for six months or more of the year. There isalso savings by a decrease in lost production, which is experienced whenwellhead boiler equipment is inoperative.

The present invention increases safety because there are no open flameson location, no pilot to light, no lighting procedures, no freezing dueto a pilot going out, the solenoid valve is fail safe, the electronicsare fail safe, and the circuit board was built in protection in theevent wires are hooked up wrong. In addition, the present invention canprovide numerous features, such as a built in solar panel chargingregulator, a green light to indicate the system is working properly or aproblem exists when the green light flashes, a reset button, and optionto wire in existing telemetry to send a signal incase of a systemshutdown, and an option to wire in a tank level gauge if the water levelfalls below the fire tube. The present invention can be used in anyboiler or gas-fired heater tube application, such as wellheads, naturalgas and natural gas liquids processing plants, natural gas and naturalgas liquids purification plants, and petrochemical complexes.

In operation, a signal from the medium to be heated, alerts the controlprocessor of the need for heat (low temperature setting). The processorthen initiates a “flame on” sequence: (1) the igniter is armed andelectrified, building rapidly to ignition temperature (the time forigniter to be brought to flame on temperature is variable, but typicallywithin twenty seconds); (2) the fuel valve is actuated open; and (3) thefuel, air mixture introduced to the igniter results in combustion. Ifthe “flame” indicator does not detect flame, the system is fully purgedfor a period of time (e.g., five minutes), and the start sequence isagain initiated. Following a number of no flame indications (e.g.,three), an alert is electronically sent to a monitoring locationspecified by the company. At sometime thereafter, a high temperaturesignal from the heated medium alerts the processor that medium is at“upper temperature” limit and the processor actuates fuel valve closure.The flame is extinguished for lack of fuel. Note that the processor iselectrified by an “in place” battery, which charged via local solarpanel.

Now referring to FIG. 1, a block diagram of a control system 100 for agas-fired heater 102 in accordance with one embodiment of the presentinvention is shown. The gas-fired heater 102 includes, in part, a heaterfire tube 104 and a flame arrester 106. A fuel supply line 108 extendsfrom the fuel source 110 through a fuel regulator 112, a fuel sourceactuator valve 114 and the flame arrester 106 into the heater fire tube104. The fuel source can be butane, propane, natural gas (raw, processedor treated) or other combustible fuel that can be ignited with a hotsurface igniter. A pilotless igniter 116 extends into the heater firetube 104 from the flame arrester 106 such that the pilotless igniter 116can initiate combustion of the fuel introduced into the heater fire tube104 by fuel supply line 108. Due to the harsh environment, the pilotlessigniter 116 is preferably a hot surface igniter having a silicon nitrideheating element that has a rated temperature of at least 1000° C. at 12volts. The igniter 116 can also function as a flame sensor or a separateflame sensor can be installed in the heater fire tube 104. As a result,the supply line 108, igniter 116 and flame sensor (not shown) aredisposed within the gas-fired heater 102. The system 100 also includesone or more power sources, such as battery 118 and solar panel 120, atemperature sensor 122 and a controller 124. The system 100 mayoptionally include a fluid level sensor 126. The battery 118, controller124 and terminal block 128 (not required, but makes installation easier)are typically installed in a weather resistant control box 130, whichcan be installed locally (e.g., mounted on the existing onsite equipmentor a stand alone pedestal or rack) or remotely (e.g., mounted in acontrol building).

The controller 124 is electrically connected to the one or more powersources (battery 118 and solar panel 120), the temperature sensor 122,the pilotless igniter 116, the flame sensor 116 and the fuel sourcevalve 114 via terminal block 128. The one or more power sources mayinclude a battery 118, a solar panel 120, a generator (not shown) or anAC electrical outlet (not shown). The selection of the power source willdepend on the site where the system will be installed. In most cases,the most cost effective and efficient power source will be a battery 118that is recharged by a solar panel 120. Similarly, standard wiring willprovide the most cost effective and efficient connection between thecontroller 124 and the temperature sensor 122, the pilotless igniter116, the flame sensor 116 and the fuel source valve 114. There may becircumstances where it is desirable and practical to use wirelesstechnology for the connection between the controller 124 and thetemperature sensor 122, the pilotless igniter 116, the flame sensor 116and the fuel source valve 114. The controller 124 may also include acommunicably connected communications interface to a computer networkconnection, a modem, a telemetry connection, a telephone line, or awireless communications link.

In operation, the controller 124 turns the pilotless igniter 116 on fora first time period and opens the fuel source valve 114 whenever thetemperature sensor 122 indicates that a temperature is less than orequal to a low temperature setting. The controller 124 also closes thefuel source valve 114 whenever the temperature sensor 122 indicates thatthe temperature is greater than or equal to a high temperature settingor the flame sensor 116 indicates that a flame has gone out. Thetemperature sensor 122 can indicate that the temperature is less than orequal to the low temperature setting by sending a low temperature signalto the controller 124, and indicate that the temperature is greater thanor equal to the high temperature setting by sending a high temperaturesignal to the controller 124. The low temperature setting and the hightemperature setting can be set at the temperature sensor 122 or thecontroller 124, depending on the sophistication of the controller 124.For example, a temperature sensor 122, such as an A25T-HL SeriesTemperature Switchgage® manufactured by FW Murphy, provides a high andlow temperature setting.

Referring now to FIG. 2, a block diagram of a controller 124 for agas-fired heater 102 in accordance with one embodiment of the presentinvention is shown. The controller 124 includes a first connector 200, asecond connector 202, a third connector 204, a fourth connector 206, afifth connector 208 and a processor 210 connected to the first 200,second 202, third 204, fourth 206 and fifth connectors 208. Theprocessor 210 can actually be two or more microprocessors that implementdifferent logic and have one or more isolated inputs with current limitprotection. Except for the first connector 200, second connector 202,third connector 204, fourth connector 206, fifth connector 208, andsixth connector 212, the controller 124 is preferably sealed to protectthe components from damage and contamination.

During operation, the processor 210 receives power from one or morepower sources (battery 118 and solar panel 120) via the first connector200 (200 a to battery 118 and 220 b to solar panel 120), turns on apilotless igniter 116 for a first time period via the third connector204 and opens the fuel source valve 114 via the fifth connector 208whenever a temperature sensor 122 indicates that a temperature is lessthan or equal to a low temperature setting via the second connector 202a. The processor 210 closes the fuel source valve 114 via the fifthconnector 208 whenever the temperature sensor 122 indicates that thetemperature is greater than or equal to a high temperature setting viathe second connector 202 b or a flame sensor 116 indicates that a flamehas gone out via the fourth connector 206. The temperature sensor 122indicates that the temperature is less than or equal to the lowtemperature setting by sending a low temperature signal (LOW) to theprocessor 210 via the second connector 202 a, and indicates that thetemperature is greater than or equal to the high temperature setting bysending a high temperature signal (HIGH) to the processor 210 via thesecond connector 202 b.

The controller 124 may also include a sixth connector (not shown)connected to the processor 210 for a communications interface (notshown), a seventh connector 212 connected to the processor 210 for afluid level sensor 126, and an overcharge protection circuit 214disposed between the first connection 202 a for the battery 118 and thefirst connection 202 b for the solar panel 120. Signal conditioners 216a, 216 b, 218 and 220 can be disposed between the processor 210 and thesecond connector 202 a for the temperature sensor 122 (LOW), the secondconnector 202 b for the temperature sensor 122 (HIGH), the fourthconnector 206 for the flame sensor 116 and the seventh connector 212 forthe fluid level sensor 126, respectively. Buffers 222 and 224 can bedisposed between the processor 210 and the third connector 204 for thepilotless igniter 116 and the fourth connector 208 for the fuel sourcevalve 114, respectively. A voltage regular 216 can be used to regulateand supply the voltage to the processor 210, signal conditioners 216 a,216 b, 218 and 220, and the buffers 222 and 224. The controller 124 mayalso include a reset switch 226 connected to the processor 210 and astatus indicator 228 connected to the processor 210.

Moreover, the present invention provides a control kit for a gas-firedheater 102 that includes a battery 118, a temperature sensor 122, apilotless igniter 116 for installation within the gas-fired heater 102,a flame sensor 116 for installation within the gas-fired heater 102 anda controller 124. The controller 124 has a first connector 200 a for thebattery 118, a second connector 202 a and 202 b for the temperaturesensor 122, a third connector 204 for the pilotless igniter 116, afourth connector 206 for the flame sensor 116 and a fifth connector 208for the fuel source valve 114. The controller 210 is configured orprogrammed to turn the pilotless igniter 116 on for a first time periodand open the fuel source valve 114 whenever the temperature sensor 122indicates that a temperature is less than or equal to a low temperaturesetting. The controller 125 is also configured or programmed to closethe fuel source valve 114 whenever the temperature sensor 122 indicatesthat the temperature is greater than or equal to a high temperaturesetting or the flame sensor 116 indicates that a flame has gone out. Thekit may also include a solar panel 120 for connection (chargingconnection 200 b) to the controller 124 such that the solar panel 120 isused to recharge the battery 118.

Now referring to FIGS. 3A and 3B, flow charts of a method 300 and 350 ofcontrolling a gas-fired heater in accordance with one embodiment of thepresent invention are shown. Using method 300, the controller turns apilotless igniter on for a first time period and opens the fuel sourcevalve whenever a low temperature signal is received in block 302, andcloses the fuel source valve whenever a high temperature signal isreceived or a flame sensor indicates that a flame has gone out in block304. Similarly, using method 350, the controller turns a pilotlessigniter on for a first time period and opens the fuel source valvewhenever a temperature is less than or equal to a low temperaturesetting in block 352, and closes the fuel source valve whenever thetemperature is greater than or equal to a high temperature setting or aflame sensor indicates that a flame has gone out in block 354. Aspreviously described, a low temperature signal is received from atemperature sensor whenever the temperature is less than or equal to thelow temperature setting, and a high temperature signal is received froma temperature sensor whenever the temperature is greater than or equalto the high temperature setting. The low temperature setting and thehigh temperature setting can be set at a temperature sensor or acontroller. Note that the present invention can be implemented using acomputer program embodied on a computer readable medium wherein theabove-described steps are implemented using one or more code segments.

Referring now to FIGS. 4A and 4B, flow charts of a method of controllinga gas-fired heater in accordance with another embodiment of the presentinvention are shown. The process starts in block 400. If a lowtemperature signal is not received, as determined in decision block 402,the process continues to check for such an occurrence. If, however, alow temperature signal is received, as determined in decision block 402,the pilotless igniter is turned on for a first time period in block 404.After a second time period has elapsed in block 406, the fuel sourcevalve is opened in block 408. If the flame is not on, as determined indecision block 410 and the pilotless igniter is not off, as determinedin decision block 412, the process loops until the flame is on or theflame is off and the pilotless igniter is off. If the flame is not on,as determined in decision block 410 and the pilotless igniter is off, asdetermined in decision block 412, the fuel source valve is closed inblock 414, and a system alert is logged or transmitted to a local orremote location in block 416. After a third time period has elapsed inblock 418, the process loops back to attempt reignition if the lowtemperature signal is still being received, as determined in decisionblock 402.

If, however, the flame is on, as determined in decision block 410, and ahigh temperature signal has not been received, as determined in decisionblock 420, the process continues to loop and check the status of theflame and whether a high temperature signal has been received. Thesituation where the flame goes out, as determined in decision block 410,was previously described. If, however, the high temperature signal isreceived, as determined in decision block 420, the fuel source valve isclosed in block 422 and the process loops back to check for a lowtemperature signal, as determined in decision block 402.

During this process, the controller may detect a system interrupt 450,such as a low voltage, a low fluid level, a processor failure, a resetbutton or a flame out. In such a case, the controller will turn thepilotless igniter off (if it is on) in block 452, close the fuel sourcevalve (if it is open) in block 454, a system alert is logged ortransmitted to a local or remote location in block 456, and the systemwill wait, shutdown and/or restart depending on the circumstances andcontroller settings in block 458. Note that the controller may disablethe fuel source valve and the pilotless igniter during a start up or lowvoltage condition.

Now referring now to FIGS. 5A and 5B, flow charts of a method ofcontrolling a gas-fired heater in accordance with yet another embodimentof the present invention are shown. The process starts by performing oneor more startup checks in block 500. If the startup checks did not pass,as determined in decision block 502, a system alert is logged ortransmitted to a local or remote location in block 504, and the systemwill wait, shutdown and/or restart depending on the circumstances andcontroller settings in block 506. If the startup checks did pass, asdetermined in decision block 502 and a low temperature signal is notreceived, as determined in decision block 508, the process continues tocheck for such an occurrence. If, however, a low temperature signal isreceived, as determined in decision block 508, the pilotless igniter isturned on for 20 seconds (a first time period) in block 510. After 10seconds have elapsed (a second time period) in block 512, the fuelsource valve is opened in block 514. If the flame is not on, asdetermined in decision block 516 and the pilotless igniter is not off,as determined in decision block 518, the process loops until the flameis on or the flame is off and the pilotless igniter is off. If the flameis not on, as determined in decision block 516 and the pilotless igniteris off, as determined in decision block 518, the fuel source valve isclosed in block 520, and a system alert is logged or transmitted to alocal or remote location in block 522. After five minutes (a third timeperiod) have elapsed in block 524, and a maximum number of reignitionattempts (e.g., three) have not been attempted, as determined indecision block 516, the process loops back to attempt reignition if thelow temperature signal is still being received, as determined indecision block 508.

If, however, the maximum number of attempts have been tried, asdetermined in decision block 526, a system alert is logged ortransmitted to a local or remote location in block 528, and the systemwill wait, shutdown and/or restart depending on the circumstances andcontroller settings in block 530. If, however, the flame is on, asdetermined in decision block 516, and a high temperature signal has notbeen received, as determined in decision block 532, the processcontinues to loop and check the status of the flame and whether a hightemperature signal has been received. The situation where the flame goesout, as determined in decision block 516, was previously described. If,however, the high temperature signal is received, as determined indecision block 532, the fuel source valve is closed in block 534 and theprocess loops back to check for a low temperature signal, as determinedin decision block 508.

During this process, the controller may detect a system interrupt 550,such as a low voltage, a low fluid level, a processor failure, a resetbutton or a flame out. In such a case, the controller will turn thepilotless igniter off (if it is on) in block 552, close the fuel sourcevalve (if it is open) in block 554, a system alert is logged ortransmitted to a local or remote location in block 556, and the systemwill wait, shutdown and/or restart depending on the circumstances andcontroller settings in block 558. Note that the controller may disablethe fuel source valve and the pilotless igniter during a start up or lowvoltage condition.

It will be understood by those of skill in the art that information andsignals may be represented using any of a variety of differenttechnologies and techniques (e.g., data, instructions, commands,information, signals, bits, symbols, and chips may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof). Likewise, thevarious illustrative logical blocks, modules, circuits, and algorithmsteps described herein may be implemented as electronic hardware,computer software, or combinations of both, depending on the applicationand functionality. Moreover, the various logical blocks, modules, andcircuits described herein may be implemented or performed with a generalpurpose processor (e.g., microprocessor, conventional processor,controller, microcontroller, state machine or combination of computingdevices), a digital signal processor (“DSP”), an application specificintegrated circuit (“ASIC”), a field programmable gate array (“FPGA”) orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. Similarly, steps of a method orprocess described herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Althoughpreferred embodiments of the present invention have been described indetail, it will be understood by those skilled in the art that variousmodifications can be made therein without departing from the spirit andscope of the invention as set forth in the appended claims.

1. A system for controlling a gas-fired heater connected to a fuelsource via a fuel source valve, the system comprising: one or more powersources; a temperature sensor; a pilotless igniter disposed within thegas-fired heater; a flame sensor disposed within the gas-fired heater;and a controller electrically connected to the one or more powersources, the temperature sensor, the pilotless igniter, the flame sensorand the fuel source valve, wherein the controller turns the pilotlessigniter on for a first time period and opens the fuel source valvewhenever the temperature sensor indicates that a temperature is lessthan or equal to a low temperature setting, and closes the fuel sourcevalve whenever the temperature sensor indicates that the temperature isgreater than or equal to a high temperature setting or the flame sensorindicates that a flame has gone out.
 2. The system as recited in claim1, wherein the one or more power sources comprises a battery, a solarpanel, a generator or an AC electrical outlet.
 3. The system as recitedin claim 1, wherein the one or more power sources comprises a batterythat is recharged by a solar panel.
 4. The system as recited in claim 1,wherein the temperature sensor indicates that the temperature is lessthan or equal to the low temperature setting by sending a lowtemperature signal to the controller, and indicates that the temperatureis greater than or equal to the high temperature setting by sending ahigh temperature signal to the controller.
 5. The system as recited inclaim 1, wherein the low temperature setting and the high temperaturesetting are set at the temperature sensor or the controller.
 6. Thesystem as recited in claim 1, further comprising: a communicationsinterface communicably connected to the controller; or a fluid levelsensor electrically connected to the controller.
 7. The system asrecited in claim 6, wherein the communications interface is a computernetwork connection, a modem, a telemetry connection, a telephone line, awireless communications link.
 8. The system as recited in claim 1,wherein the pilotless igniter comprises a hot surface igniter having asilicon nitride heating element.
 9. The system as recited in claim 1,wherein the pilotless igniter has a rated temperature of at least 1000°C. at 12 volts.
 10. The system as recited in claim 1, wherein the flamesensor is the pilotless igniter.
 11. The system as recited in claim 1,wherein gas-fired heater is used at a wellhead, a natural gas or naturalgas liquids processing plant, a natural gas or natural gas liquidspurification plant, or a petrochemical complex.
 12. An apparatus forcontrolling a gas-fired heater connected to a fuel source via a fuelsource valve, the apparatus comprising: a first connector; a secondconnector; a third connector; a fourth connector; a fifth connector; anda processor connected to the first, second, third, fourth and fifthconnectors, such that during operation, the processor receives powerfrom one or more power sources via the first connector, turns on apilotless igniter for a first time period via the third connector andopens the fuel source valve via the fifth connector whenever atemperature sensor indicates that a temperature is less than or equal toa low temperature setting via the second connector, and closes the fuelsource valve via the fifth connector whenever the temperature sensorindicates that the temperature is greater than or equal to a hightemperature setting via the second connector or a flame sensor indicatesthat a flame has gone out via the fourth connector.
 13. The apparatus asrecited in claim 12, wherein the temperature sensor indicates that thetemperature is less than or equal to the low temperature setting bysending a low temperature signal to the processor via the secondconnector, and indicates that the temperature is greater than or equalto the high temperature setting by sending a high temperature signal tothe processor via the second connector.
 14. The apparatus as recited inclaim 12, further comprising: a signal conditioner disposed between theprocessor and the second connector or the fourth connector; a bufferdisposed between the processor and the third connector or the fifthconnector; a voltage regular disposed between the first connector andthe processor; a sixth connector connected to the processor for acommunications interface; a seventh connector connected to the processorfor a fluid level sensor; a reset switch connected to the processor; ora status indicator connected to the processor.
 15. The apparatus asrecited in claim 12, wherein the processor comprises two or moremicroprocessors that different logic and have one or more isolatedinputs with current limit protection.
 16. The apparatus as recited inclaim 12, wherein the apparatus is sealed except for the first, second,third, fourth and fifth connectors.
 17. A method for controlling agas-fired heater connected to a fuel source via a fuel source valve, themethod comprising the steps of: turning a pilotless igniter on for afirst time period and opening the fuel source valve whenever atemperature is less than or equal to a low temperature setting; andclosing the fuel source valve whenever the temperature is greater thanor equal to a high temperature setting or a flame sensor indicates thata flame has gone out.
 18. The method as recited in claim 17, furthercomprising the steps of: receiving a low temperature signal from atemperature sensor whenever the temperature is less than or equal to thelow temperature setting; and receiving a high temperature signal from atemperature sensor whenever the temperature is greater than or equal tothe high temperature setting.
 19. The method as recited in claim 17,fturther comprising the step of setting the low temperature setting andthe high temperature setting at a temperature sensor or a controller.20. The method as recited in claim 17, wherein the fuel source valve isnot opened until a second time period has elapsed after the pilotlessigniter was turned on.
 21. The method as recited in claim 17, furthercomprising the step of transmitting operational data to a remotelocation.
 22. The method as recited in claim 17, further comprising thestep of disabling the fuel source valve and the pilotless igniter duringa start up or low voltage condition.
 23. The method as recited in claim17, further comprising the step of closing the fuel source valvewhenever the flame sensor indicates that the flame was not created andthe igniter is off.
 24. The method as recited in claim 23, furthercomprising the step of transmitting an alarm signal.
 25. The method asrecited in claim 23, fturther comprising the step of turning thepilotless igniter on for the first time period and opening the fuelsource valve after a third time period has elapsed since the fuel sourcevalve was closed.
 26. The method as recited in claim 17, furthercomprising the step of turning the pilotless igniter off (if it is on)and closing the fuel source valve (if it is open) whenever a systeminterrupt is detected.
 27. The method as recited in claim 26, whereinthe system interrupt comprises a low voltage, a low fluid level, aprocessor failure, a reset button or a flame out.
 28. A computer programembodied on a computer readable medium for controlling a gas-firedheater connected to a fuel source via a fuel source valve, the computerprogram comprising: a code segment for turning a pilotless igniter onfor a first time period and opening the fuel source valve whenever atemperature sensor indicates that a temperature is less than or equal toa low temperature setting; and a code segment for closing the fuelsource valve whenever the temperature is greater than or equal to a hightemperature setting or a flame sensor indicates that a flame has goneout.
 29. A control kit for a gas-fired heater connected to a fuel sourcevia a fuel source valve, the kit comprising: a battery; a temperaturesensor; a pilotless igniter for installation within the gas-firedheater; a flame sensor for installation within the gas-fired heater; acontroller having a first connector for the battery, a second connectorfor the temperature sensor, a third connector for the pilotless igniter,a fourth connector for the flame sensor and a fifth connector for thefuel source valve, wherein the controller is configured to turn thepilotless igniter on for a first time period and open the fuel sourcevalve whenever the temperature sensor indicates that a temperature isless than or equal to a low temperature setting, and close the fuelsource valve whenever the temperature sensor indicates that thetemperature is greater than or equal to a high temperature setting orthe flame sensor indicates that a flame has gone out.
 30. The kit asrecited in claim 24, further comprising: a solar panel; and a chargingconnector on the controller for the solar panel such that the solarpanel is used to recharge the battery.